Method of transferring images produced by liquid development

ABSTRACT

In an electrophotographic process, visual images obtained by developing electrostatic latent images with a liquid developer are transferred to a transferring paper having oil absorbing coefficient ranging from 1.0 X 10 4 to 5.0 X 10 2 cm./sec. and smoothness by Bekk tester ranging from 30 to 150 seconds.

Unite States Patent 1191 Saito et a1.

[ METHOD OF TRANSFERRING IMAGES PRODUCED BY LIQUID DEVELOPMENT [76]Inventors: Takashi Saito; Shuniti Kubu, both of Tokyo, Japan; CanonKabushiki Kaisha, 03, Tokyo, Japan [22] Filed: Aug. 30, 1971 [21] Appl.No.: 176,096

[30] Foreign Application Priority Data Sept. 4, 1970 Japan 45-77872 [52]US. Cl. 117/37 LE, 96/1 LY, 96/1.4, 355/10, 117/155 UA [51] Int. Cl G03g13/16 [58] Field of Search 117/37 LE; 96/1 LY, 1.4; 355/10; 118/637,DIG. 23

[56] References Cited UNITED STATES PATENTS 3,251,688 5/1966 Mihajlov96/1 LY 1451 May 21, 1974 3,419,411 12/1968 Wright 96/1.4 3,556,7841/1971 Robinson et ul..... 96/1.4 3,663,219 5/1972 Takahnshi 117/37 LET879009 10/1970 Stuudenmayer et a1. 1 17/37 LE T887027 6/1971 Chechak117/37 LE Primary Examiner-William D. Martin Assistant Examiner-M.Sofocleous Attorney, Agent, or FirmFitzpatrick, Cclla, Harper & ScintoABSTRACT 4 Claims, 5 Drawing Figures PA TENIEB MAY 2 1 i974 SHEET 1 0F 2METHOD OF TRANSFERRING IMAGES PRODUCED BY LIQUID DEVELOPMENT BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention relates to amethodof transferring visual images produced by liquid-developingelectrostatic latent images formed on a surface of anelectrophotographic photosensitive member.

2. Description of the Prior Art Heretofore, there have been investigatedvarious transferring methods for images developed by a liquiddevelopment. For example, a backside of a transferring paper is earthedby a roller or corona discharging; a bias voltage is applied between aphotosensitive member and a transferring paper to enhance thetransferring efficiency; or the liquid developer is improved to obtain agood transferring property of a developed image to a transferring paper.

However, there have not been obtained any knowledges of transferringpapers used for transferring an image developed by liquid development inelectrophotographic processes. When usual papers used for transferringimages produced by dry development is used in transferring imagesproduced by liquid development, the transferring efficiency is extremelylow and uniform transferred images are not obtained. Furthermore, theliquid developer is absorbed into the transferring paper in a largeamount and therefore, it takes disadvantageously much time at the dryingand fixing stages. The transferring paper uneconomically takes out muchamount of the liquid developer and this results in formation of a largeamount of vapor of the carrier liquid in the drying stage and this isnot desirable from hygienic point of view.

The transferring of images developed by liquid development inelectrophotographic processes is considered to be effected mainly byelectrophoresis of toner particles in a liquid (a carrier liquid of aliquid developer) present between a surface of a photosensitive memberand a transferring paper. A transferring paper capable of absorbing alarge amount of liquid, i.e., a paper of low liquid holdout, decreasesan amount of the carrier liquid upon transferring operation and therebydisturbs the electrophoresis of toner particles. As the result, thetransferrring efficiency is lowered to a great extent and furtheremorethere occurs non-uniform transferring.

In addition, after transferring, the degree of wetness on the surface ofphotosensitive member becomes low and this does not favor the cleaningoperation.

In transferring images obtained by liquid development, it is necessaryto pay attention to a fixing property as well as the above mentionedtransferring characteristics of paper.

The inventors have found that transferring papers of low oil absorptionproperty favor the transferring property, but show low fixability fortransferred images. This seems due to a fact that toner particles hardlypermeates the fibers composing a paper and toner parti cles can not befixed to the paper in such a way that the toner particles take root inthe fibers. When a surface of paper is coated with a resin so as toprevent permeation of a carrier liquid, the surface property isrelatively good, but such treatment lowers the fixability.

Any way, a fixing agent contained in toner can not impart sufficientfixability. However, the present inventors have found that fixability ismarkedly improved by imparting a certain roughness to a surface of apaper of low oil absorption property. In other words it has been nowfound that low oil absorption property and rough surface areindispensable conditions for a transferring paper used in transferringof images developed by a liquid developer.

SUMMARY OF THE INVENTION According to the process of this invention,there is used a transferring paper having oil absorption coefficientranging from 1.00 X 10 4 to 5.0 X 10' cm./sec., preferred with from 1.0X 10 to 1.5 X 10 cm./sec. and smoothness by Bekk tester ranging from 30to 150 seconds, preferably from 50 to seconds upon transferring an imageobtained by developing an electrostatic latent image by a liquiddeveloper to a transferring paper.

When the oil absorption coefiicient is higher than 5.0 X 10 cm./sec.,the transferred image is scratchy and not practical. On the contrary,when the oil absorption coefficient is less than 1.0 X 10" cm./sec., thetransferring property is good, but there appear many pinholes caused byliquid soaked in the paper and it takes long time to dry. And furtherthe cleaning of the photosensitive member is very difficult after thetransferring.

When the smoothness by Bekk tester is higher than seconds, the fixingproperty is so low that a practical copy can not be obtained. On thecontrary, when the smoothness is less than 30 seconds, there appearmissing dots.

It is an object of this invention to provide a method of transferring animage obtained by developing an electrostatic latent image formed on aphotosensitive member in an electrophotographic process.

It is another object of this invention to provide a method oftransferring an image in high efficiency giving a transferred image ofhigh quality.

It is a further object of this invention to provide a transferringmethod by which there is obtained a good fixation of a transferringpaper.

It is still another object of this invention to provide a transferringmethod in which the cleaning of a photosensitive member surface is veryeasy after the transferring.

It is still a further object of this invention to provide a transferringmethod in which the amount of liquid developer absorbed to thetransferring paper is small and the drying time can be short andmoreover the con sumption of liquid developer is low.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows schematically a crosssection of an apparatus used for a process according to this invention;

FIG. 2 is an enlarged cross section of a part of the apparatus shown inFIG. 1;

FIG. 3 is a graph showing a surface property of a paper measured'by aneedle touch method; and

FIG. 4 schematically shows an apparatus for measuring oil absorptioncoefficient.

DESCRIPTION OF THE PREFERRED EMBODIMENT A transferring paper used inthis invention may be obtained by adjusting the oil absorptioncoefficient to a range as defined in the claims in the following ways.

1. Incorporating in high ratio a fiber material capable of strengtheningbeating degree such as cotton material, e.g., rag, hemp. soft wood andthe like to make the tissue dense, i.e., lowering permeability.

2. Incorporating a filler such as resin to the tissue or surface, orsizing or coating to lower the permeability.

Measuring method of oil absorption coefficient is illustrated in FIG. 4.One drop of Isopar G 23 (about 0.004 c.c.) is dropped onto a samplepaper 27 placed between spacer rings 26 on a support table 28 by usingan injector (2 c.c.) 24 having a needle 25 of subcutaneous Lure Type /a.The dropped portion is observed from back side of the paper through amirror 29. A light source is designated as 22.

When Isopar G permeates the sample paper, the corresponding portion ofthe sample paper becomes transparent. Firstly, the sample becomes partlytransparent (pinhole) and then the whole dropped portion (about -15 mmin diameter) becomes transparent. There is measured a period of timefrom a time when a drop of Isopar G reaches the sample paper to a timewhen the drop liquid permeates throughout the sample portioncorresponding to the dropped portion. The measuring is made with 0.1second unit. One sample paper is measured with respect to 10 differentdropped portions and the averaged time is designated as T. The thicknessof the sample paper is measured according to .IIS-P81 l8 and isdesignated as H (cm.).

An oil absorption coefficient, a, is represented by the formula:

or H/T (cm/sec.)

where a is calculated up to significant figure of two digits.

The smoothness of Bekk tester of paper is measured in accordance with.IIS-P81l9.

Referring to FIG. 3, the two graphs show the surface property oftransferring papers measured by a needle touch method. FIG. 3 (a) showsa relatively smooth surface which is of about 500 seconds by Bekk testerand FIG. 3 (b) shows a rough surface which is of about 30 seconds byBekk tester.

For the same toner, the transferring paper (a) shows an extremely lowfixing property while the transferring paper (b) shows a sufficientfixing property. This good fixing property of the rough surface paperappears to be due to the fact that the toner particles are attached toand buried in the lower portion of the uneven surface. The minimumvisible point is composed of gathering of several tens of toners havingdiameter of about 1-10 11.. Therefore, some of such toners enter thelower portions of the uneven surface and attaches one another as if thetoners spreaded deep root in the paper tissue. On the contrary, thetoner particles simply cover the surface of the transferring paper incase of (a) above, but there are hardly present entangling between thetoner and the paper surface. Usual printing paper has naturally asurface roughness, but the surface roughness is not generally compatiblewith low oil absorption property.

The transferring paper used in this invention may be prepared by coatingthe surface of paper with a resin so as to improve the oil absorptionsproperty of usual printing paper and further by using a paper makingwire net of an appropriate mesh (about 65 mesh) upon making the paper oradjusting appropriately the press roller pressure upon calendering so asto lower the oil absorption property and, in addition, make the surfaceappropriately rough. By using the transferring paper thus prepared,there can be effected uniform transferring in high transferring yieldand furthermore the carrier liquid amount permeating a transferringpaper is so small that the drying time can be reduced.

As the result, a transferring method in liquid developing process can berealized in which the fixing is excellent and cleaning of the surface ofphotosensitive member is very easy after transferring due to hightransferring efficiency.

FIG. 1 shows schematically an apparatus carrying out transferring ofimages developed by a liquid developing process. A photosensitive plate1 has a three-layer structure composed of a conductive base 1a, aphotoconductive layer lb, and an insulating layer 1c. An electrostaticimage may be formed on photosensitive plate 1 by a process, for example,that disclosed in Japanese Pat. Publication No. 4223910 or 4324748. Thatis, the insulating layer 10 is given a uniform charge of one polarity asshown by 2 to bind an electric charge to a portion in photoconductivelayer lb and near the interface between photosensitive layer lb andinsulating layer 1c, and then a DC. voltage having a polarity oppositeto that charged on insulating layer 10, or AC corona discharge isapplied to insulating layer 1c simultaneously with projecting a lightimage as shown in 3 to form an electrostatic latent image on insulatinglayer 10. A blanket irradiation 4 is then applied to release excesscharge bound in photoconductive layer lb to increase the contrast of theelectrostatic latent image. The resulting electrostatic latent image isdeveloped by a liquid developer 5 and excess liquid developer is removedby postcharge 9. The developed image is transferred onto a transferringpaper 8 by using a transferring roller 6 and then the surface ofphotosensitive member 1 is cleaned with a cleaning device 7.

Referring to FIG. 2, a developed image as shown in FIG. 1 is transferredto a transferring paper 8 by contacting the transferring paper 8 withthe developed image surface by using a transferring conductive roller 14earthed. A base la is also earthed so that a part of positive charge 16in base 1a induced by negative charge 13 on the surface is divided intothe conductive roller 14 and distributed as shown by 17, and most oftoners 18 are attracted by the charge 17, moved and transferred to atransferring paper 8 by electrophoresis.

If the oil absorption property of transferring paper 8 is high in suchtransferring, a thin layer of carrier liquid 5 (e.g., highly insulatingliquid such as kerosene, is absorbed to atransferrring paper 8 to reducethe amount of the liquid necessary for electrophoresis transferring. Asa result, thetransferring is effected by a partial electrophoresistransferring and a kind of pressure transferring and thereby only asmallamount of the toner is transferred and in addition the image thustransferred is not uniform.

An appropriate amount of liquid developer is necessary upon transferringfor the purpose of obtaining high transferring efficiency. Therefore, atransferring paper of low oil absorption is required. Such transferringpaper of low oil absorption hardly contains a carrier liquid therein sothat drying and fixing are very rapid. For example, cool wind orallowing to stand is sufficient to dry and fix. Therefore, formation ofhazardous vapor is so little that employing the low oil absorption paperis advantageous from sanitary point of view. Furthermore, a thin layerof liquid remains on the photosensitive member surface aftertransferring and this facilitates cleaning.

The transferring method of the present invention is also effective onefor a corona bias transferring method in which a transferring paper islaid on a developed image and a corona discharging is applied from theback side since the transferring in corona bias method is also a kind ofelectrophoreis transferring mechamism.

The following examples are given for illustrating the present invention,but by no means for limiting the present invention.

EXAMPLE 1 Electrostatic images were produced on a photosensitive membercomposed of a conductive support, a photoconductive layer and aninsulating layer by using a method as illustrated in FIG. 1 and theresulting electrophotographic images were developed with a liquiddeveloper prepared as shown below Carbon hluck l.5g. Linseed oilmodified alkyd resin 3g. Lecithin 40mg.

The mixture of the above components was ballmilled with 30g. of Solvesso100 (Trade name) for about 12 hours and then dispersed into 1 liter oflsopar G (Trade name, supplied by Esso) by using a homomixer to producethe liquid developer.

The images developed on the surface of the photosensitive member weresubjected to a charge squeezing treatment by a corono charging of 6KV toremove the excess lsopar G.

On the other hand, a paper of high density and surface smoothness of Isecond (Bekk tester) was prepared by forming a fiber composition ofthree parts of rag contents and seven parts of soft wood contents,strengthening the beating degree, preparing a paper therefrom, applyinga machine coat by using a solution of vinyl acetate resin in toluene inan amount of 10 lg./m. and then treating with calender.

The resulting paper had a thickness of 0.047 mm. and an oil absorptioncoefficient of 3 X '4 cm./sec. This paper was used as a transferringpaper. It was closely contacted with the developed images after chargesqueezing treatment and then peeled off rolling an electroconductiverubber roller which back surface was earthed to produce clear and highlydense transferred images. The fixing property of the transferred imagewas also very good.

EXAMPLE 2 A paper (oil absorption coefficient of about 7 X 10" cm./sec.)of mediocre beating degree prepared from eight parts of hard woodcontents and two parts of soft wood contents was coated with an aqueousdispersion of polyvinyl alcohol and clay (solid matter weight ratio,1:5) in an amount of 2-3g./m by using a size-press. The resulting coatedpaper was subjected to a light calender treatment to obtain atransferring paper having an oil absorption coefficient of 6.0 X 10cm./sec. and smoothness of Bekk tester of 60 seconds.

The transferring paper can give a clear, highly dense transferred imageof high fixing property when used in an electrophotographic process asshown in Example 1.

EXAMPLE 3 The same paper as in Example 2 (oil absorption coefficient,about 7.0 X 10 cm./sec.) was coated with an aqueous dispersion of starchand clay (solid matter weight ratio, 1:1) in an amount of 8 g./m byusing a size-press. The resulting paper was calendered to produce atransferring paper having an oil absorption coefficient of 5.0 X 10cm./sec. and smoothness by Bekk tester of 55 seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring prop erty and fixability.

EXAMPLE 4 The same paper as in Example 2 (oil absorption coefficient,about 7.0 X 10' cm./sec.) was coated with an aqueous dispersion ofcarboxymethyl celulose and barium sulfate (solid matter weight ratio, 2:l in an amount of 8 g./m by using a size-press. The resulting paper wascalendered to produce a transferring paper having an oil absorptioncoefficient of 3.5 X 10 cm./sec. and smoothness by Bekk tester ofseconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Examplel to produce a transferred image of hightransferring property and fixability.

' EXAMPLE 5 The same paper as in Example 2 (oil absorption coefficient,about 7.0 X 10 cm./sec.) was coated with an aqueous dispersion ofmethylol melamine, cation starch and clay (solid matter weight ratio,3:225) in an amount of 6 g./m by using a size-press. The resulting paperwas calendered to produce a transferring paper having an oil absorptioncoefficient of 2.0 X 10' cm./sec. and smoothness by Bekk tester ofseconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 6 The same paper as in Example 2 (oil absorption coefficient,about 7.0 X 10' cm./sec.) was coated with an aqueous dispersion of anacrylic resin emulsion, polyvinyl alcohol and titanium dioxide (solidmatter weight ratio, M21) in an amount of 4 g./m-'. by using asizepress. The resulting paper was calendered to produce a transferringpaper having an oil absorption coefficient of 8.0 X 10 cm./sec. andsmoothness by Bekk tester of 55 seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 7 EXAMPLE 8 The same paper as in Example 2 (oil absorptioncoefficient, about 7.0 X 10" cm./sec.) was coated with an aqueousdispersion of NBR latex, casein and clay (solid matter weight ratio,111:2) in an amount of g./m by using a size-press. The resulting paperwas calendered to produce a transferring paper having an oil absorptioncoefficient of 1.5 X cm./sec. and smoothness by Bekk tester of 35seconds. Then the transferring paper was subjected to anelectrophotographic process as described in Example 1 to produce atransferred image of high transferring property and fixability.

EXAMPLE 9 The same paper as in Example 2 (oil absorption coefficient,about 7.0 X 10" cm./sec.) was coated with an aqueous dispersion of anacryl-vinylacetate copolymer emulsion, starch and titanuim dioxide(solid matter weight ratio, 2:1:1) in an amount of 5 g./m by using asize-press. The resulting paper was calendered to produce a transferringpaper having an oil absorption coefficient of 9.0 X 10 cm./sec. andsmoothness by Bekk tester of 65 seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and flxability.

EXAMPLE 10 An ordinary grade paper (oil absorption coefficient, 2.0 X 10cm./sec.) was machine-coated with an aqueous dispersion of an acrylicacid ester and titanium dioxide (solid matter weight ratio, 1:1) in anamount of 8 g./m and then calendered lightly to obtain a transferringpaper having an oil absorption coefficient of 4.5 X 10- cm./sec. andsmoothness by Bekk tester of 90 seconds.

Then the transferring paper was subjected to an electrophotographic,process as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 1 1 An ordinary grade paper was machine-coated with an aqueousdispersion of high styrene latex and NBR latex (solid matter weightratio, 1:1) in an amount of 10 g./m and then calendered lightly toobtain a transferring paper having an oil absorption coefficinet of 5.0X

10' cm./sec. and smoothness by Bekk tester of seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 12 An ordinary grade paper was machine-coated with an aqueousdispersion of a polyvinyl acetate emulsion, polyvinyl alcohol and bariumsulfate (solid matter weight ratio, 1:1:2) in an amount of 15-20 g./mand then calendered lightly to obtain a transferring paper having an oilabsorption coefficient of 1.0 X 10" cm./sec. and smoothness by Bekktester of 150 seconds.

Then the transferring paper was subjected to an electrophotgraphicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 13 An ordinary grade paper was machine-coated with an aqueousdispersion of acrylic acid ester and starch (solid matter weight ratio,1:1 in an amount of 10 g./m and then calendered lightly to obtain atransferring paper having an oil absorption coefficient of 8.0 X 10"cm./sec. and smoothness by Bekk tester of 75 seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability;

EXAMPLE 14 An ordinary grade paper was machine-coated with an aqueousdispersion of NBR latex, methyl cellulose and clay (solid matter weightratio, 2:3:5) in an amount of 10 g./m and then calendered lightly toobtain a transferring paper having an oil absorption coefficient of 7.5X 10 cm./sec. and smoothness by Bekk tester of seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 15 An ordinary grade paper was machine-coated with an aqueousdispersion of a vinyl acetate-styrene copolymer emulsion and bariumsulfate (solid matter weight ratio, 1:3) in an amount of 10 g./m andthen calendered lightly to obtain a transferring paper having an oilabsorption coefficient of 7.0 X 10 cm./sec. and smoothness by Bekktester of 1 10 seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a transferred image of hightransferring property and fixability.

EXAMPLE 16 An ordinary grade paper was machine-coated with a solution ofacrylic acid ester in toluene in an amount of 30 g./m lightly calenderedand matted by a sand blast method to obtain a transferring paper havinguneven- 4 ness of average 20p. on the surface, oil absorptioncoefficient of 5.0 X 10 cm./sec. and smoothness by Bekk tester of 45seconds.

Then the transferring paper was subjected to an electrophotographicprocess as described in Example 1 to produce a clear transferred imageof high transferring property and fixability.

The following Table l is given for summarizing the results in the abovementioned examples and comparing them with control shown in ComparisonExamples COMPARISON EXAMPLE 4 A paper composed of eight parts of hardwood and b l I two parts of soft wood and having a mediocre beatingTable 1 Density of Density of Oil Absorption Smoothness TransferringTransferred Image after Coefficient of by Bekk Method Image Fixing Test:Irwfem'nglapen Tester Example (cm/sec.) (sec.) 1 1.50 1.41 3.0 X 10 1002 1.45 1.40 6.0 X 10 60 3 1:38 1.34 5.0 X 10 55 4 1.26 1.24 3.5 X 10 705 1.12 1.04 2.0 X 10 100 6 1.40 1.38 8.0 X 10" 55 7 1.37 1.29 1.0 X 10'120 8 1.20 1,19 1.5 X 10? 35 9 1.56 1.48 9.0 X 10" 65 '10 1.45 1.37 4.5X 10* 90 11 1.42 1.35 5.0 X 10' 100 12 1.50 1.40 1.0 X 10 150 13 1.351.32 8.0 X 10 75 14 1.42 1.35 7.5 X 10" I 15 1.38 1.31 7.0 X 10' 110 161.51 1.50 5.0 X 10' 45 Comparison Example (Man Pinholes in the Image) 31.25 1.22 5.0 X 10 (Remarkable Missing dots) 4 1.07 0.98 4.0 X 10" 200(Density of image was measured by a reflecting densitometer. The densityof image before transferring was constantly 70.)

COMPARISON EXAMPLE-l As the transferring paper, there was used a papercomposed of eight parts of hard wood andtwo parts of soft wood, mediocrebeating degree, oil absorption coefficient of 7.0 X 10 cm./sec., andsurface smoothness by Bekk tester of 40 seconds and anelectrophotographic process was carried out in a way similar to Examplel.

COMPARISON EXAMPLE 2 An ordinary grade paper was machine-coated with andegree was strongly calendered to produce a paper aqueous dispersion ofa polyvinyl chloride emulsion,

polyvinyl alcohol and barium sulfate (solid matter wei-. ght ratio,1:12) in an amount of 30g./m. and calendered to produce a paper havingoil absorption coefficient of 6.0 X 105 cm./sec, and smoothness by Bekktester of 400 seconds. The resulting paper was used as a transferringpaper and an electrophotographic process was carried out in a waysimilar to Example 1.

COMPARISON EXAMPLE 3 An ordinary grade paper was machine coated with anaqueous dispersion of a polyvinyl acetate emulsion, polyvinyl alcohol,and barium sulfate (solid matter h! 21. 1z. 2Q n.as m q2t2flQs-. m39aniiseesls hvw sseifiri r sses--.

having oil absorption coefficient of 4.0 X 10' cm./sec, and smoothnessby Bekk tester of 200 seconds The resulting paper was used as atransferring paper in an electrophotographic process similar to that ofExample I The fixing test was carried out as follows. Atransferringpaper after image-transferred and dried was placed on ahorizontal surface plate and a soft paper having a rough surface, KojinWiper (trade name, supplied by 'Kojin) of about 8 cm was placed thereonand further an aluminum block was placed on the soft paper of roughsurface. The resulting total load was about 12g./cm The soft paper ofrough surface and the aluminum block were fixed in such away that theycan not move to the horizontaldirection and then the transferring paperwas pulled at a speed of about 7 cm./sec. and this pulling was repreatedfive times.

It is clear from the results as shown above that a paper having oilabsorption coefficient ranging from 1.0 X 10" to 5.0 X10 cm./sec.,particularly from' 1.0 .x 10 to 1.5 X 10 cm./sec., is of high'transferring property and further a paper having smoothness by Bekktester of 30 150 seconds, particularly, 50

A paper having oil absorption coefficient higher than 5.0 X cm./sec.(of. Comparison Example 1 shows an extremely bad transferring property.On the contrary, when the oil absorption coefficient is less than 1.0 X10 cm./sec., there disadvantageously appear many pinholes in thetransferred image.

When the smoothness by Bekk tester is higher than 150 seconds, thefixing property is lower. When the smoothness by Bekk tester is lessthan seconds, the surface of paper is uneven and many missing dotsappear.

We claim:

1. A method of transferring an image developed by a liquid developerwhich comprises developing an electrostatic latent image formed on asurface of a photosensitive member by an electrophotographic process byusing a liquid developer for electrophotography composed of charged finetoner dispersed in a highly insulating liquid and transferring byelectrophoresis the de- 12 veloped image to a transferring paper havingan oil absorption coefficient from about 1.0 X 10' to 5.0 X 10' cm./sec.and smoothness by Bekk tester from about 30 to 150 seconds, in thepresence of the highly insulating liquid on a surface of thephotosensitive member.

2. A method of transferring an image according to claim 1 wherein theoil absorption coefficient is from about 1.0 X 10* to 1.5 X 10 cm./sec.and the smooth ness by Bekk tester from about 50 to seconds.

3. A method of transferring an image according to claim 1 wherein thephotosensitive member is a threelayered photosensitive member composedof a conductive support, a photoconductive layer and an insulating layerlaminated according to the above-mentioned order.

4. A method of transferring an image according to claim 3 wherein thetransferring paper contains a resin. 1

2. A method of transferring an image according to claim 1 wherein theoil absorption coefficient is from about 1.0 X 10 4 to 1.5 X 10 2cm./sec. and the smoothness by Bekk tester from about 50 to 100 seconds.3. A method of transferring an image according to claim 1 wherein thephotosensitive member is a three-layered photosensitive member composedof a conductive support, a photoconductive layer and an insulating layerlaminated according to the above-mentioned order.
 4. A method oftransferring an image according to claim 3 wherein the transferringpaper contains a resin.